Miscarriage is the spontaneous loss of a pregnancy before the 20th week. About 10 to 20 percent of known pregnancies end in miscarriage. But the actual number is probably much higher because many miscarriages occur so early in pregnancy that a woman doesn't even know she's pregnant.

Miscarriage is a somewhat loaded term — possibly suggesting that something was amiss in the carrying of the pregnancy. This is rarely true. Most miscarriages occur because the fetus isn't developing normally. However, because these abnormalities are rarely understood, it's often difficult to determine what causes them.

Miscarriage is a relatively common experience — but that doesn't make it any easier. Take a step toward emotional healing by understanding what can cause a miscarriage, what increases the risk and what medical care might be needed.

Most miscarriages occur before the 12th week of pregnancy.

Signs and symptoms of a miscarriage might include:

Vaginal spotting or bleeding

Pain or cramping in your abdomen or lower back

Fluid or tissue passing from your vagina

If you have passed fetal tissue from your vagina, place it in a clean container and bring it to your health care provider's office or the hospital for analysis.

Keep in mind that most women who experience vaginal spotting or bleeding in the first trimester go on to have successful pregnancies.

Abnormal genes or chromosomes

Most miscarriages occur because the fetus isn't developing normally. Problems with the baby's genes or chromosomes are typically the result of errors that occur by chance as the embryo divides and grows — not problems inherited from the parents.

Examples of abnormalities include:

Blighted ovum. Blighted ovum occurs when no embryo forms.

Intrauterine fetal demise. In this situation the embryo is present but has stopped developing and died before any symptoms of pregnancy loss have occurred.

Molar pregnancy. A molar pregnancy is a noncancerous (benign) tumor that develops in the uterus. A molar pregnancy occurs when there is an extra set of paternal chromosomes in a fertilized egg. This error at the time of conception transforms what would normally become the placenta into a growing mass of cysts. This is a rare cause of pregnancy loss.

Maternal health conditions

In a few cases, a mother's health condition might lead to miscarriage. Examples include:

Uncontrolled diabetes

Infections

Hormonal problems

Uterus or cervix problems

Thyroid disease

What does NOT cause miscarriage

Routine activities such as these don't provoke a miscarriage:

Exercise

Having sex

Working, provided you're not exposed to harmful chemicals or radiation.

Various factors increase the risk of miscarriage, including:

Age. Women older than age 35 have a higher risk of miscarriage than do younger women. At age 35, you have about a 20 percent risk. At age 40, the risk is about 40 percent. And at age 45, it's about 80 percent. Paternal age also might play a role. Some research also suggests that women who become pregnant by older men are at slightly higher risk of miscarriage.

Previous miscarriages. Women who have had two or more consecutive miscarriages are at higher risk of miscarriage.

Chronic conditions. Women who have a chronic condition, such as uncontrolled diabetes, have a higher risk of miscarriage.

Smoking, alcohol and illicit drugs. Women who smoke during pregnancy have a greater risk of miscarriage than do nonsmokers. Heavy alcohol use and illicit drug use also increase the risk of miscarriage.

Weight. Being underweight or being overweight has been linked with an increased risk of miscarriage.

Some women who miscarry develop a uterine infection, also called a septic miscarriage. Signs and symptoms of this infection include:

Fever

Chills

Lower abdominal tenderness

Foul-smelling vaginal discharge

If you have signs or symptoms of miscarriage, contact your health care provider right away. Depending on the circumstances, you might need immediate medical care.

Here's some information to help you get ready for your appointment, and what to expect from your health care provider.

What you can do

Before your appointment, you might want to:

Ask about pre-appointment restrictions. In most cases you'll be seen immediately. If that's not the case, ask whether you should restrict your activities while you wait for your appointment.

Find a loved one or friend who can join you for your appointment. Fear and anxiety might make it difficult to focus on what your health care provider says. Take someone along who can help remember all the information.

Write down questions to ask your health care provider. That way, you won't forget anything important that you want to ask, and you can make the most of your time with your health care provider.

Below are some basic questions to ask your health care provider about miscarriage:

What are the treatment options?

What kinds of tests do I need?

Can I continue to do my usual activities?

What signs or symptoms should prompt me to call you or go to the hospital?

Do you know what caused my miscarriage?

What are my chances for a successful future pregnancy?

In addition to the questions you've prepared, don't hesitate to ask other questions during your appointment — especially if you need clarification or you don't understand something.

What to expect from your doctor

Your health care provider is likely to ask you a number of questions, too. For example:

When was your last menstrual period?

Were you using any contraceptive methods at the time you likely conceived?

When did you first notice your signs or symptoms?

Have your symptoms been continuous or occasional?

Compared with your heaviest days of menstrual flow, is your bleeding more, less or about the same?

Have you had a miscarriage before?

Have you had any complications during a previous pregnancy?

Do you have any other health conditions?

Do you know your blood type?

Your doctor may do a variety of tests:

Pelvic exam. Your doctor will check to see if your cervix has begun to dilate.

Ultrasound. This helps your doctor check for a fetal heartbeat and determine if the embryo is developing normally.

Blood tests. If you've miscarried, measurements of the pregnancy hormone, beta HCG, can occasionally be useful in determining if you've completely passed all placental tissue.

Tissue tests. If you have passed tissue, it can be sent to the laboratory to confirm that a miscarriage has occurred — and that your symptoms aren't related to another cause of pregnancy bleeding.

Possible diagnoses include:

Threatened miscarriage. If you're bleeding but your cervix hasn't begun to dilate, there is a threat of miscarriage. Such pregnancies often proceed without any further problems.

Inevitable miscarriage. If you're bleeding, your uterus is contracting and your cervix is dilated, a miscarriage is inevitable.

Incomplete miscarriage. If you pass some of the fetal or placental material but some remains in your uterus, it's considered an incomplete miscarriage.

Missed miscarriage. The placental and embryonic tissues remain in the uterus, but the embryo has died or was never formed.

Complete miscarriage. If you have passed all the pregnancy tissues, it's considered a complete miscarriage. This is common for miscarriages occurring before 12 weeks.

Septic miscarriage. If you develop an infection in your uterus, it's known as a septic miscarriage. This can be a very severe infection and demands immediate care.

Threatened miscarriage

If you're having a threatened miscarriage, your health care provider might recommend resting until the bleeding or pain subsides. You might be asked to avoid exercise and sex as well. Although these steps haven't been proved to reduce the risk of miscarriage, they might improve your comfort. It's also a good idea to avoid traveling — especially to areas where it would be difficult to receive prompt medical care.

Miscarriage

With ultrasound, it's now much easier to determine whether the embryo has died or was never formed. Either finding means that a miscarriage will definitely occur. In this situation you might have several choices:

Expectant management. If you have no signs of infection, you might choose to let the miscarriage progress naturally. Usually this happens within a couple of weeks of determining that the embryo has died. Unfortunately it might take up to three or four weeks. This can be an emotionally difficult time. If expulsion doesn't happen on its own, medical or surgical treatment will be needed.

Medical treatment. If, after a diagnosis of certain pregnancy loss, you'd prefer to speed the process, medication can cause your body to expel the pregnancy tissue and placenta. Although you can take the medication by mouth, your health care provider might recommend inserting the medication vaginally to increase its effectiveness and minimize side effects such as nausea and diarrhea. For about 70 to 90 percent of women, this treatment works within 24 hours.

Surgical treatment. Another option is a minor surgical procedure called suction dilation and curettage (D&C). During this procedure, your health care provider dilates your cervix and removes tissue from the inside of your uterus. Complications are rare, but they might include damage to the connective tissue of your cervix or the uterine wall. Surgical treatment is needed if you have a miscarriage accompanied by heavy bleeding or signs of an infection.

Physical recovery

Physical recovery from miscarriage in most cases will take only a few hours to a couple of days. In the meantime, call your health care provider if you experience heavy bleeding, fever or abdominal pain.

Expect your period to return within four to six weeks. You can start using any type of contraception immediately after a miscarriage. However, avoid having sex or putting anything in your vagina — such as a tampon — for two weeks after a miscarriage.

Future pregnancies

It's possible to become pregnant during the menstrual cycle immediately after a miscarriage. But if you and your partner decide to attempt another pregnancy, make sure you're physically and emotionally ready. Ask your health care provider for guidance about when you might try to conceive.

Keep in mind that miscarriage is usually a one-time occurrence. Most women who miscarry go on to have a healthy pregnancy after miscarriage. Less than 5 percent of women have two consecutive miscarriages, and only 1 percent have three or more consecutive miscarriages.

If you experience multiple miscarriages, generally more than three in a row, consider testing to identify any underlying causes — such as uterine abnormalities, coagulation problems or chromosomal abnormalities. In some cases your health care provider might suggest testing after two consecutive losses. If the cause of your miscarriages can't be identified, don't lose hope. About 60 to 70 percent of women with unexplained repeated miscarriages go on to have healthy pregnancies.

Emotional healing can take much longer than physical healing. Miscarriage can be a heart-wrenching loss that others around you might not fully understand. Your emotions might range from anger and guilt to despair. Give yourself time to grieve the loss of your pregnancy, and seek help from loved ones.

Often, there's nothing you can do to prevent a miscarriage. Simply focus on taking good care of yourself and your baby. Seek regular prenatal care, and avoid known risk factors — such as smoking and drinking alcohol. If you have a chronic condition, work with your health care team to keep it under control.

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